Exploring the sources of p-mode frequency shifts in the CoRoT target HD 49933

作     者：Zhi-E Liu Shao-Lan Bi Wu-Ming Yang Tan-Da Li Kang Liu Zhi-Jia Tian Zhi-Shuai Ge Jie Yu 

作者机构：Department of Astronomy Beijing Normal University Key Laboratory of Solar Activity National Astronomical Observatories Chinese Academy of Science 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2014年第14卷第6期

页      面：683-692页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：Supported by the National Natural Science Foundation of China 

主　　题：stars: individual (HD 49933)    stars: evolution    stars: oscillation   stars: modeling 

摘      要：Oscillations of the solar-like star HD 49933 have been thoroughly observed by CoRot. Two dozen frequency shifts, which are closely related to the change in magnetic activity, have been measured. To explore the effects of magnetic activity on frequency shifts, we calculate frequency shifts for the radial and l=1 p-modes of HD 49933 with the general variational method, which evaluates the shifts using a spa- tial integral of the product of a kernel and some sources. The theoretical frequency shifts reproduce the observation well. The magnitudes and positions of the sources are determined according to a χ2 criterion. We predict the source that contributes to both the l = 0 and l= 1 modes is located 0.48 - 0.62 Mm below the surface of the star. In addition, based on the assumption that A0 is proportional to the change in the MglI activity index △iMgⅡ, we obtain that the change in MgⅡ index between the minimum and maximum of the cycle during the period of HD 49933 is about 0.665. The magnitude of the frequency shifts compared to the Sun already demonstrates that HD 49933 is much more active than the Sun, which is further confirmed in this pa- per. Furthermore, our calculation of the frequency shifts for l = 1 modes indicates the variation of turbulent velocity in the stellar convective zone may be an important source for the l = 1 shifts.